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Sunday, 24 February 2013

Fat Innkeeper Worm

Image: Rosario Beach Marine LaboratoryHead on the right

They'll have you as a guest, but be prepared for some extremely distasteful personal habits. And don't ask where the food came from...
Fat Innkeepers are several marine worms in the genus Urechis, itself within a group called Echiura, the Spoon Worms. Spoon Worms are not segmented, but for a long time they were considered a strange group of annelids. These days, some DNA evidence suggests they should be a whole other phylum, as closely related to molluscs as they are to annelids.

Image: Rosario Beach Marine LaboratoryActual fatness may vary

In short, it's complicated. And lots of scientists are working really hard to ensure that one day I will be able to shave down the above paragraph into two, short sentences. I'm not even paying them!

I kind of hope for the annelid/mollusc thing. Fat Innkeepers in particular mix and meld some of the more reprobate features of worms and slugs. And yet, partly due to these very nastiphiliac tendencies, the Innkeeper's inn is one of the most hip happening joints around town! So let's take a look, shall we?

The first thing to understand is that Fat Innkeepers are burrowers. The actual worm only reaches about 20 cm (8 in) long, but their U-shaped burrow can be several feet deep. It's made in the kind of soft, sandy mud you get in estuaries and beaches. The Innkeeper teases its way through the sediment with its smooth, muscular body, saving money on couches because the walls and floor are all comfy and cozy.

After about 40 seconds you get to see the Innkeeper's short proboscis.It looks... suggestive

Both sides of the U go to the surface. On one side is just a hole, on the other is a kind of chimney. The collection of food begins at this chimney. Bring a mop.

First, the Fat Innkeeper spins a net of mucus across the chimney entrance. Next, it moves backward, pulling the snot-net and adding yet more mucus. Eventually it forms a kind of snot-funnel, the open end attached to the chimney, the other in its mouth.

Work that flab!

The Innkeeper now pumps water into its burrow by peristalsis, a wave of muscle contraction running all the way down its body like an earthworm or a lonesome piece of intestine trying to make its way in a big, cruel world.

Water passes through the chimney and the snot-net before flowing out of the burrow via the other exit. However, like some tiny, aquatic snot-spider's web, plankton of all kinds gets trapped in the snot-net.

Eventually it all gets clogged up with food and the Fat Innkeeper finds it more and more difficult to keep the water flowing. And when things get difficult, it's time to eat. The Fat Innkeeper devours the entire net and almost everything in it, only discarding the crumbs which are simply too big to eat.

And this is why the Fat Innkeeper is so popular. There are tiny pea crabs who run around the burrow tearing into anything they can find. A certain scale worm remains in direct contact with the Innkeeper to ensure it doesn't miss out on those discarded scraps. There's even a clam that keeps out of the burrow itself, but is buried close enough to extend its siphons into it. That way it can take in the food and clean water that rushes by but remain far beneath the dangers of the sea floor.

Image: Mary Jo AdamsArrow Goby, Clevelandia ios

And there's a goby. These little bottom-dwelling fish rush in and out of all sorts of other people's burrows, be it to escape predators or to hide out during low tide.

It's incredibly rude, really. The Fat Innkeeper doesn't seem to mind, though. Indeed, a lot of these so-called guests are basically doing housework. They're more like home help who get paid with food and housing. That old Innkeeper is more wily than he looks! Capitalist Worm, surely?

They even have a kind of toilet. Sort of. I mean, they already have a U-bend, right? Unfortunately they just don't flush it very often. Instead, they allow a pile of faeces and burrowing material grow and grow until it becomes completely intolerable. Then, finally, they get their arse into gear. Top gear. The Innkeeper squeezes its body and a great gust of water shoots out from its anus, aimed squarely at that rubbish heap. It does this repeatedly until the whole pile of refuse is fired right out of the burrow.

I just push a button and water magically appears to make other stuff magically disappear. Given the options, I vote magic.

With the astounding (also intelligent and technologically advanced) laziness on display here, it won't surprise you to learn that males and females reproduce by throwing their eggs and sperm into the sea like so many faecal pellets. The larvae drift around for a couple months before they settle and get digging.

Oh, and eagle-eyed or dirty-minded readers may be relieved to know that the Fat Innkeeper Worm was known as the Penis Fish long before you started sniggering. And like many a penis fish, it's delicious served raw, stir-fried or dried and powdered for its savoury taste.